This invention relates to dispensers and more particularly to a selector valve for selection of one of a plurality of fluids for dispensing or mixing with another fluid through a venturi eductor system.
Such selector valves typically allow an operator to select and dispense one particular chemical or fluid at a time, while closing off access to any of the other fluid sources available for selection.
One such prior selector valve typically included a static body having several inlet ports and one outlet port, and a rotatable valve core with passages to allow selective connection of a selected inlet port with the outlet port. Sealing was provided by a spring loaded, o-ring sealed, Teflon plunger carried in the rotatable core and bearing against the face of the static member.
While such selector valves allow selective connection and dispensing, they have several inherent disadvantages.
First, such valves have parts that are vulnerable to the undesirable effects of the dispensed chemicals, such as abrasion or chemical attack. When chemicals come in contact with o-ring seals, for example, this can erode the o-rings and cause the seal to weaken over time. Therefore, these o-rings occasionally must be checked and replaced.
Second, it is important to be able to efficiently change over from one selected chemical to another. The volume of the prior chemical in the system which must be purged delays the dispensing of the second chemical in unadulterated form. Thus, because of the distance the selected fluid must travel within the selector valve system, the system may contain a significant amount of residual chemical after the user has selected a new inlet port, requiring the user to spend time purging the line.